The invention relates generally to power-driven conveyors and, more particularly, to roller-belt conveyors used to merge multiple lanes of articles into a single file.
Many conveying applications require that articles traveling different paths be merged into a single file. One example of a merge conveyor is described in U.S. Pat. No. 7,426,992, “Systems and Methods for Providing an Improved Timing Conveyor,” issued Sep. 23, 2008, to Matthew L. Fourney. FIG. 15 of that patent shows a timing conveyor section comprising two side-by-side timing conveyors that receive articles at irregular intervals. Each timing conveyor accelerates the articles to designated positions that are staggered from conveyor to conveyor. The staggering of the designated positions allows the two timing conveyors to alternately feed articles at regular intervals to a singulating conveyor, which merges the spaced articles into a single file.
One typical singulating conveyor includes a flat-top belt with a plow, or guide, arranged across the belt to merge the articles to an exit region of the belt. Although plows are made of materials having low coefficients of friction, articles still tend to pivot at the plows and re-orient themselves or to move backward slightly upon contact. These effects can overcome the precise timing of the delivery of articles from the timing conveyor section and set lower bounds on the spacing of the delivery of articles by the timing conveyor and, consequently, upper bounds on throughput.
Another typical singulating conveyor uses an angled-roller belt to singulate articles without a plow, as described in U.S. Pat. No. 6,758,323, “Singulating Conveyor,” issued Jul. 6, 2004 to Mark B. Costanzo. The singulating belt described has actuated belt rollers on each half that rotate obliquely toward the center line of the belt as it advances. The rollers are plastic with a fairly low coefficient of friction and ride on actuating rollers or bearing surfaces in the carryway. Slip between the rollers and the conveyed articles can compromise the precise article timing set by the timing conveyor. These angled-roller belt singulators are more expensive than flat-top belts with plows and typically require a longer distance to singulate articles.
Thus, there is a need for a simple merge conveyor that can accommodate high throughput.